Dumbbell Nan-Kilo Moteru?

The "body-building comedy" centers around Hibiki Sakura, a high school girl who loves eating, and Akemi Sōryūin, the beautiful and charismatic student council president who has a muscle fetish. The staff describes the story:
"Hibiki … Are you fat again?"
A friend's cruel words which cut like a knife into the heart of Hibiki Sakura, a high school girl who loves to eat. Hibiki decided to go on a diet to be absolutely thin by summer vacation, but she cannot keep exercising right alone. That's when Hibiki found herself before a training gym! Upon joining the gym, Hibiki meets her beautiful and charismatic student council president Akemi Sōryūin and steps into the intense yet enjoyable world of weight-training.